The KneeLecture 11

The Knee Complex

the knee is a large complex joint frequently injured during sport participation

the knee is positioned between the two longest bones in the body - the femur and the tibia creating potential for high torque’s

this factor coupled with poor bony stability makes the knee very susceptible to injury

Tibiofemoral Joint

articulation of the distal femur and proximal tibia form a modified hinge joint

movement in 2 planes - Flex /Ext , lnt /Ext rotation

because of the size and shape of the condyles the tibia can rotate on the femur

this lateral rotation of the tibia on the femur (only a few degrees) provides a locking of the knee or a "screwing-home mechanism"

stability and support provided by menisci and supportive ligaments

Menisci are fibrocartilage discs that are attached

to the tibia by coronary ligaments and joint capsule

they are thicker along the lateral margin and thinner medially

- the medial meniscus is injured more frequently than the lateral meniscus

blood supply only in outer 1/3 of meniscus

Medial Meniscus 'C' shaped, strongly

attached to the tibial surface therefore less mobile

one reason injured more often

also attached to the joint capsule (medially)

Lateral Meniscus more complete

( almost circle shaped) loosely attached to

tibial surface - less commonly injured

Functions of the Menisci

stability - deepens socket and wedge shaped to prevent A-P motion

-increase surface area of femoral condyles

shock absorption provide nutrition because it promotes

synovial fluid flow and distribution - proprioception function through its innervation

Meniscal Tears

associated with ligaments disruptions, degenerative changes, repetitive stress secondary to chronic ligamentous laxity, isolated or repetitive rotational stresses

Ligaments of the Knee

the stabilizing role of the ligaments that cross the knee is very significant

two major ligaments are the anterior and posterior cruciates ( called cruciate because they cross each other inside the knee joint)

two other ligaments are the medial and lateral collateral ligaments

Anterior Cruciate Ligament separated into to bundles according to

their functions, ( not really separate) spiral around one another, insert as one

board ligament spiral arrangement plus the broad attachment allow ACL to provide stability through out the full ROM

ACL most common and serious injury to the knee

susceptible to injury with a valgus force, external rotation strong quad contraction of knee hyperextension

ACL is subject to deceleration injuries , internal tibial torque is the most dangerous loading mechanism, particularly when combined with an anterior tibial force

Posterior Cruciate Ligament

not as commonly injured as ACL stronger and shorter than the ACL prevents posterior tibial translation and

knee hyperextension common mechanism collision or fall on

tibial tuberosity

Medial Collateral Ligament

provide valgus, external rot support (note ACL is also very imp in this function)

basically a thickening of the medial capsule

superficial layer and a deep layer

Lateral Collateral Ligament

cord like structure considered to be extra capsular

less commonly injured b/c of varus mechanism and less debilitating

Dynamic Knee Support

ITB, hamstrings, quads , gracilis , gastroc the key to injury rehab and prevention

Bursae Suprapatellar, prepatellar, superficial

infrapatellar and deep infrapatellar i) suprapatellar largest in the body lies

between the femur and the quads tendon of the rectus femoris

ii) prepatellar - located between skin and anterior surface of patella

allowing for movement of then skin over the patella

iii) superficial infrapatellar - located between the skin and the patellar tendon

-inflammation this are due to excessive kneeling referred to as housemaid's knee

iv) deep infrapatellar - located between the tibial tuberosity and the patellar tendon

reduces friction between tendon and bony tuberosity

Patellofemoral Joint patella articulates

with the femur

Patella largest sesamiod bone in the body located within the quads tendon articulates with the femoral condyles patella facets -under surface of patella

Common Injuries to the Knee

1) Contusions and Bursitis result from a compressive force - a fall ,

a kick generally they are locally tender, with

pain, swelling and ecchymosis Bursitis - may be caused by a direct

trauma or possibly infection swelling usually occurs over a 24 hour

period Rx - PIER - protection - may need

draining but this may add complications

2) Ligament Injuriesone plane instabilities

i) MCL pain and swelling usually found along

the medial joint line ii) LCL pain and swelling are found on the

lateral aspect of the knee

MCL injuries

straight lateral forces or valgus causes tension on the MCL

Signs and symptoms

medial knee pain Swelling Medial joint laxity RX - PIER, hinge knee brace for stability , crutches , most MCL injuries are treated non surgically

http://www.youtube.com/watch?v=_fxKCDkOiJs&feature=related

http://www.youtube.com/watch?v=ubP-1WaFeEc&feature=related

LCL injuries

medial forces or varus force produces tension on the LCL

Much rarer injury than MCL

Signs and symptoms

Lateral knee pain Localized swellingLateral joint laxity RX: PIER, hinge knee brace for stability , crutches , most LCL injuries are treated non surgically

ACL injuries

ACL prevents forward translation of the tibia on the femur, also assists with controlling valgus and varus forces , and helps prevent hyperextension

MOI : damage to the ACL usually results from a cutting or turning maneuver, landing off balance or a sudden deceleration

s/s Pain , instability , swelling , may often hear

or fell a pop in the knee, decreased ROM and function

pain described as being felt deep in the knee or on either side of the patellar tendon

joint effusion is usually bloody and fairly rapid onset

PCL injury

PCl prevents the tibia from moving posterior on the femur

MOI: a direct blow to the anterior tibia ( dashboard injury) , or hyperflexion or hyperextension

s/s Large tense knee effusion Discomfort attempting to flex the knee beyond 90

degrees RX: PIER, crutches , referral to surgeon , however this is

not often repairs..

Multidirectional Instabilities – injuries to multiple structures

http://www.youtube.com/watch?v=6evRcL3QMns

http://www.youtube.com/watch?v=uuoj_HFG5Z0&NR=1

First Aid Care ( knee ligaments )

Apply ice and compression immediately , brace to protect , crutches

If knee unstable , have athlete seek proper medical advice

Most ACL tears are referred to a orthopedic surgeon, due to the continued instability of the knee

Repairs….

3) Meniscal Injuries compression, tensile and shearing force

often cause damage to the mensci tears may be - longitudinal , bucket handle

, horizontal or parrot-beak medial mensicus is more often damaged more common in men between the age of

21-40 and women between 11- 20 joint line pain and general joint effusion,

pain with rotations and extreme flexion

individual may experience clicking , popping or grinding

the knee may give way or buckle the individual may have difficulty doing

squats and or duck walking the meniscal tear may lodge in the joint

causing locking surgery is usually necessary to unlock this

condition mensici become stiffer and less resilient with age

RX – PIER – rest and time possibly surgery

First Aid Care

Apply ice and compression immediately ,, crutches

If knee blocked or locked , have athlete seek proper medical advice ASAP

Repairs….

4) Patellofemoral Stress Syndrome

usually caused by weakness in the VMO or lateral retinaculum is too tight

this condition is more commonly found in women due to a higher Q angle

Q angle is the angle between the line of the quads ( RF) and the patellar tendon

a Q-angle of less than 13 and more than 18 may predispose the athlete to PFS

pain may be dull and aching generally in the centre of the knee or on lateral edge of patella

point tenderness usually over lateral edge of patella, often associated with anterior knee pain

crepitus or grinding often present - especially upon compression of the patella

Rx - PIER - NSIADS -taping- VMO strengthening , education

5) Subluxation or Dislocation of Patella commonly occurs during

deceleration or cutting maneuver

patella moves laterally and may tear medial retinaculum

leading to an audible pop and a collapse of the knee

the patella may remain displaced or reduce itself

may need to be reduced by doctor pain and swelling , Rx- PIER, immobilization, exercise and

education

First Aid Care

Apply ice and compression immediately , splint leg, crutches

Arrange transportation to nearest medical facility

6) Patella Tendinitis

aka jumpers knee patellar tendon

becomes inflamed and tender from repeated jumping (eccentric knee extension activities)

pain located on inferior pole of patella pain increases on stairs, after prolonged

sitting and during resisted knee extension as condition worsens time and duration of

pain may change or worsen Rx- PIER, NSAIDS, modalities, exercise

and stretching..

7) Osgood-Schlatter Disease traction type injury to the tibial tuberosity

where the patellar tendon inserts more common in boys aged 10-15 pain and swelling are present with

activity usually diminish with rest in cases with long duration the tibial

tuberosity may become enlarged

condition usually rectifies itself (within 12 to 24 months) with age and closure of the growth plate

Rx – symptomatic and self limiting

8) Unhappy triad Medial meniscus Anterior cruciate ligament and Medial collateral ligament

Possible Factors Influencing Increased rate of ACL injuries in Women

Intrinsic Factors Ligament size Ligament laxity Intercondylar notch dimensions Limb alignment ( wider pelvis, genu

valgum , external tibial torsion) Estrogen levels

Extrinisic Factors Level of skill Level of experience Shoe friction Ankle braces Stylistic differences in sport play

Plant and cut, straight leg landing, one step stop landing , pivoting with sudden deceleration

Muscle strength imbalances (eccentric hamstrings strength relative to eccentric quad strength )